Image processing method and image processing apparatus

Abstract

An image processing method includes the steps of: separating a luminance signal from a color signal of an original image, and multiscale retinex processing only the luminance signal; and producing an image based on the multiscale retinex processed luminance signal and the color signal of the original image.

1. An image processing method comprising:
 separating a luminance signal from a color signal of an original image, and multiscale retinex processing only the luminance signal; and  
 producing an image based on the multiscale retinex processed luminance signal and the color signal of the original image.  
 
     
     
       2. An image processing method according to  claim 1 , further comprising normalizing the multiscale retinex processed luminance signal based on a gain and an offset. 
     
     
       3. An image processing method according to  claim 1 , wherein a one-dimensional function having a symmetric property is used as a surround function for the multiscale retinex processing. 
     
     
       4. An image processing method according to  claim 3 , wherein a part of the one-dimensional function in a range, such that the one-dimensional function has a symmetric property, is converted into a table. 
     
     
       5. An image processing method according to  claim 1 , further comprising performing a one-dimensional convolution operation in the multiscale retinex processing. 
     
     
       6. An image processing apparatus, comprising:
 a multiscale retinex processing section for separating a luminance signal from a color signal of an original image, and for multiscale retinex processing only the luminance signal;  
 a first memory for storing a plurality of predetermined constants for use in the multiscale retinex processing; and  
 a second memory for storing a size of the original image and the luminance signal of the original image,  
 wherein an image is produced based on the multiscale retinex processed luminance signal and the color signal of the original image.  
 
     
     
       7. An image processing apparatus according to  claim 6 , wherein the plurality of predetermined constants comprise a number of multiscales, a scaling variable, and a weighting factor. 
     
     
       8. An image processing apparatus according to  claim 6 , wherein the multiscale retinex processed luminance signal is normalized based on a gain and an offset. 
     
     
       9. An image processing apparatus according to  claim 8 , further comprising a third memory for storing the normalized, multiscale retinex processed luminance signal. 
     
     
       10. An image processing apparatus according to  claim 6 , wherein a one-dimensional function having a symmetric property is used as a surround function for the multiscale retinex processing. 
     
     
       11. An image processing apparatus according to  claim 10 , wherein part of the one-dimensional function in a range, such that the one-dimensional function has a symmetric property, is converted into a table. 
     
     
       12. An image processing apparatus according to  claim 6 , wherein a one-dimensional convolution operation is performed in the multiscale retinex processing.